Bill rather longer than head, cleft to eyes, very stout at base,
tapering to the decurved, but not hooked, tip. Nostrils abortive.
Gular sac moderate, naked. Wings rather long, pointed. Tail long,
stiff, cuneate, twelve to fourteen feathered. Feet nearly beneath
centre of equilibrium. General configuration goose-like … _Sulidæ_.
Bill several times longer than head, slender but strong,
depressed, perfectly straight, with small distinct hooked nail at
end. Nostrils very small. Gular sac enormous. Mandibular rami
meeting only at tip. Wings extremely long, with upward of forty
remiges. Tail short, rounded, of twenty or more feathers. Legs
beneath centre of equilibrium, extremely short and stout …
_Pelicanidæ_.
Bill about as long as head, stout, straight, scarcely tapering,
strongly hooked. Nostrils abortive. Gular sac moderate, but
evident; mostly naked. Wings short. Tail large, fan-shaped,
scansorial, of twelve to fourteen broad stiff feathers, exposed
to the base. Legs inserted far behind centre of equilibrium …
_Graculidæ_.
Bill rather longer than head, slender, perfectly straight,
tapering to an acute tip. Gular sac small. Nostrils minute. Wings
and tail, and general configuration, as in the last … _Plotidæ_.
Bill much longer than head, straight, stout, strongly hooked.
Nostrils very small. Gular sac well developed. Wings exceedingly
long, strong, and pointed. Tail exceedingly long, deeply forked.
Feet extraordinarily short; tarsi partly feathered … _Tachypetidæ_.
Bill about as long as head, straight, stout, tapering to an acute
tip. Nostrils small. Gular sac rudimentary, feathered. Wings
moderate, pointed. Tail short, but with two central feathers
extraordinarily prolonged and filamentous. Feet small, beneath
centre of equilibrium … _Phæthontidæ_.